Friday, 24 June 2016

Week 12 of the transect walking season

We have reached mid-summer and the season at Newhaven's Castle Hill LNR is moving on apace. The clifftops are heading into their peak flowering season: Common Bird's-foot Trefoil, Horseshoe Vetch and Sedum make shining fulvous and citrine splashes of colour on the cliffs and offer nectar to a thousand-and-one pollinating insects. The pollen-eating Swollen-thighed Beetle (Oedemera nobilis) can be found on bramble blossom, oxeye daisy and various umbellifers, the aggressive males bundling rivals off their territories. On the north slope haws are already forming where only weeks ago the trees were adorned in bridal white blossom.

The transect-walking season is also approaching its mid-point and we continue to feel a sense of disappointment that there are not more butterflies on the wing. The weather was not bad during today's walk with unbroken sunlight for the duration, but a fresh breeze was blowing in off the sea, sending most butterflies and moths to ground along the exposed cliffs. June is a mid-point for adult butterflies - the eye in the year's butterfly storm. The June Gap is a time when the first waves of emergent adults have passed over and when their offspring are feeding-up and spinning-up prior to taking to taking wing in the high summer sky. Few adult butterflies are seen during the June Gap.The Large Skipper is one butterfly which bucks the trend. This is an insect of rough grassy places which feeds as a caterpillar on cock's-foot grass and is present in a single brood from late-May or June through to August. It is a conspicuous, territorial and pugnacious butterfly and it should reach its peak at Castle Hill in the next week or two. Meadow Browns are making a cautious start to their adult season and they will gradually increase over the next month before building towards late-summer abundance. The first brood of Speckled Woods is now declining and, although numbers never completely disappear throughout the season, we will need to wait for about six weeks to see the next spike in numbers. The leafy paths which criss-cross the north slope of the reserve provide the dappled shady habitat which makes this one of the commoner butterfly species here.A male Cuckoo was seen flying near to the Lookout during the walk, preparing to make its return journey to sub-Saharan Africa. The season really is moving on.Butterflies (5 species)

A favourite lunchtime ritual is to sit and read a book in the Southover Grange Gardens. When the weather permits, I sit on the grass with my back to the old mulberry, reputed to be older than 350 years, against the encircling metal fence which protects the gnarled boughs of the tree from all but the most determined of the town's Bohemian toddlership (the fence's horizontal metal rails are springy and yield comfortably against the back). An auspicious spot close to the edge of shade provided by the gently umbrageous mulberry offers the best conditions when the weather is warm and light of wind.

Today, beneath a sky with only a few high, hazy clouds, the weather is warm and the leaves flutter only enough to remind the visitor that the view is real and not a detail in a fine artwork. The Gardens are one of Lewes's finest features, a sanctuary. Balls, bicycles and bow-wows are banned from here. There are plenty of other places for those recreational staples outside of the Gardens; within though is a space for calm and quiet contemplation. An item of work is on my mind today and hinders progress with my open book, which rests indifferently on my lap. An image of a map, a remnant of my morning's work, is proving hard to send away. My trance is broken by a Blackbird which swoops between the v of two trees down into the Gardens from Elm Grove, which is elevated above and opposite the boundary wall. The thought and the Blackbird coalesce in my mind to create a fresh contemplation: what does that Blackbird's map of the world look like?

A human map of the Grange Gardens shows three points of entry and egress; paths around, alongside and between the grass and flowers usher the pedestrian to all areas within; unwritten rules (do not walk here!) are manifest alongside the areas of formal bedding, around the mulberry and at the face of the fenced barrier which runs alongside both banks of the Winterbourne stream (finally running itself into a dribble following a months-long plethora); and the walled Knot Garden, the benches, the terrace of the Grange and the little tea kiosk tempt the hurried and fleet of foot to linger and meditate awhile.

The Blackbird sees things differently. The tapering space between trees are its way in. Natural selection has made this a life or death consideration and the sense in taking the humble route low over vegetation has spared those like-minded individuals who are alert to the dangers, real or perceived, and weeded out those who are less discreet. The gaps in the trees: when have I ever seen them through a Blackbird's eyes? It is revelatory! A footpath must be as obscure to a Blackbird's eye as is a v between two trees to a human's. A Wren makes its slow, furious way across open ground and disappears into the same v from which the Blackbird appeared. Now a Jackdaw alights on the ground and I see that its triangulation points within the gardens are the benches as it hawks for fallen morsels. Its beady eye focuses on me - or my sandwich, which I realise is hanging half-eaten in my hand. Jacks and the Garden's grey squirrels could navigate by the same map, although the squirrels would keep their buried treasure to themselves, but add a thin and tangled scrawl of byways along any of the countless branches strong enough to withstand their avoirdupois. High, high above us the Swifts wheel and cavort. I can just about hear them screeching. How does their map appear? Their flight is the line which joins a dot-to-dot of swarming insects. Now a single Buzzard, higher still than the Swifts, is seen elevating its way along the midday thermals - the cartographer of buoyant air who paints for unseeing eyes contours of spiralling heat. Watching these animals' movements reveals features otherwise hidden in and above the landscape.

My attention is brought back down to earth by a Cinnabar moth as it helter-skelters its way erratically over the grass, its scarlet hindwings warning would-be predators of its cyanotoxic innards. A Holly Blue darts along the treeline. These and other pollinators' maps are oblivious to the concept of the human byway; their maps are painted with influorescences in ultra-violet shades which carry heavy-scent promises of nectar; each corolla a corona. Their cartographers are the plants themselves, their artistic styles and symbols having been shaped over more than 100 million years of coevolution.

From my patch of grass I see through fresh eyes how the Grange Gardens' blank canvas has been daubed in all places by nature's sage surveyors. Back at ground level, my own map forgotten by my diversion around and above the Gardens, I return to my sandwich and book before navigating back to the office.

Wednesday, 15 June 2016

I cannot tell why Nuctenea umbratica, the Walnut Orb-weaver, is my favourite spider; it just is; it always has been. One could be forgiven for thinking this spider a sinister-looking dame (it's usually a female which is seen): it's abdomen is shiny, stubble-haired, flattened and pitted (these pits, or sigilla, indicate the muscle bases which pull the abdomen flat), it has an alarming zig-zagging oak-leaf pattern or folium around its abdomen and it slinks into the shade during the daytime, emerging only at dusk to weave its silky orb upon which, once complete, it rests in the centre of, darkly, waiting for supper. The reality is that it is no more sinister than many invertebrates and the female, like many spider species, is a devoted mother.

The scientific name, Nuctenea umbratica, is interesting and instructive (I apologise to the reader who understands Latin as a language!): I was tempted to think of the first name as being derived from noctem (night), but this is wrong because nuce or nux translates literally as 'nut', and tenea (less obviously) as 'to hold', 'grasp' or 'possess' - so a possible reference to being nut-like. The second half of the binome, umbratica, is more familiar and means 'sheltered' (umbraticus meaning 'in the shade'). This translation describes both the spider's appearance and habits well, as does the acronym of its vernacular name: WOW!

This is a common and widespread spider, a member of the Araneidae family, which has 3100 members worldwide, including another with wow-factor - the stunning Wasp Spider (Argiope bruennichi). In its natural environment umbratica tucks its flattened self away during the daytime into small apertures behind tree bark, although I have seen it more often on wooden gates, fenceposts and signposts, where nooks and crannies provide an acceptable alternative. They emerge at dusk to weave a fresh web and are often found in little communities of a few or several spiders. Most of the webs I find are about 30cm in size, but they are reported to stretch to more than double this size to 70cm. Typical prey are night-flying insects such as moths. Females are often seen in springtime guarding an egg sac, as seen in the photograph below, which was taken close to home at Mount Pleasant in 2011.

Female umbratica guarding an egg-sac on a gate-post in 2011

The sexes are dimorphic, the female being much larger than the male at about 14mm compared with the smaller male, which is 8 to 9mm. This is a common feature of spider species. Females are apparently active year-round, with males appearing in early summer.

This spider is capable of biting humans, although reports of bites are rare. Venom is, after all, a precious resource and most spiders will bite in defence only when they feel threatened. The wound can burn and itch and form a fiery lesion, but it is not a serious injury. The spider is much more likely to feign death when disturbed and abseil on a silken thread away from danger to the ground, its legs tucked in tight to its body. Most of the time the spider will sit motionless and pose for a photograph. They were once a common sight in my garden but they seem to have declined during the past two or three years, their places having been taken by an ever-expanding colony of Steatoda nobilis (False Widow). I wonder if my favourite spider is being out-competed where the two species coexist?

Should you go dusking for glow-worms, Ghost Moths or Nightjar in June, it is well worth shining your light onto wooden field-furniture for a chance of glimpsing this secretive and beautiful little orb spider with the wow-factor.

Wednesday, 8 June 2016

Butterflies and moths recorded during May 2016

Vine's Rustic (Hoplodrina ambigua)

There has in recent posts been a burgeoning use of the word average. May was, until the 29th, an average month. That is how it felt anyway. Average when compared with the records I have collected in all the months of May since I began recording moths and butterflies at home and in the field. The start of May 2016 was nice and warm but a northerly airflow dominated after this and temperatures were generally cool - dare I say below average.

So let's take a look at some Maytime averages, starting at the moth trap. Over the years I have operated my trap 21 nights of the month on average - on about two out of every three nights. This year I ran my moth trap every night during May.

I have recorded a total of 345 butterfly and moth species during previous May-times, with an average of 133 species each year and 1356 individuals. This May I saw a slightly above average 150 species and 1613 individuals. Thirteen of the species recorded had not previously been seen during May-time. Of the ten most abundant species seen this year, some were on a par with the previous ten years' average: Heart and Dart (110), Dingy Skipper (51), Shuttle-shaped Dart (42) and Small White (42); but three of the remaining species were significantly more numerous this May than in the past: Diamond-back Moth (202) (average 9), Light Brown Apple Moth (119) (average 38) and White-shouldered House Moth (43) (average 6).

There are good reasons why the Diamond-back and White-shouldered House Moth were so much more abundant this year: the first is currently undergoing a mass immigration from the continent - probably the greatest example in the Sussex record (the total of 202 was the thin end of the wedge, the tip of the iceberg, the i of the idiom) - and the second was more numerous because adults were emerging from either a sack of grass clippings which was being stored in my shed or from a mouse nest beneath the shed which I have been tolerating (I like mice). Part of my evening ritual each night was to pot up fresh adults (moths, not mice) from the inside of the shed window and release them into the garden - many of whom eschewed the moth trap light and flew elsewhere, never to be seen again. One interesting observation made of these moths was the dimorphism between individuals (see the photograph below for an example). The third species which was much more numerous than its average number, the Light Brown Apple Moth, an adventive species accidentally introduced to the UK from Australia in the 1950s and now a pest of orchards, is less easy to explain. One assumes it has benefitted from the mild winter. It has had an above average year.

An example of dimorphism in the White-shouldered House Moth (Endrosis sarcitrella)

Amongst the four migrant species seen, the Diamond-back and Red Admiral were much more numerous than usual, whereas the Silver Y and White-point were seen very much in average numbers.

Five-spot Ermel (Ethmia terminella)

The nationally scarce species of moths and butterflies I saw were few. The Duke of Burgundy and Adonis Blue were seen away from Newhaven at Heyshott and Mill Hill respectively. Of the three moths, Ethmia terminella was by far the most welcome and only the second individual I have ever seen. Aethes williana and Platyedra subcinerea are always a welcome sight, but Newhaven is blessed with established colonies and their appearance each year.

There is one final point to make about averages, and that is that I put in an above average effort this May. I ran the trap each night, walked two transect routes at Castle Hill LNR, surveyed four other locations around Newhaven and enjoyed guided walks at Heyshott, Shoreham's Mill Hill and Newhaven's Bollen's Bush. It's hardly work though, is it?

As a postscript regarding the Diamond-back Moth immigration, I have during the first week of June seen more than 11,000 individuals, 4500 of which have been counted in my moth trap. I can predict with some confidence, therefore, that June is looking decidedly above average.

Rustic Shoulder-knot (Apamea sordens)

The full list for May 2016

Butterflies (20 species)

Dingy Skipper
(Erynnistages)51

Grizzled
Skipper (Pyrgusmalvae)14

Orange-tip (Anthochariscardamines)11

Large White (Pierisbrassicae)10

Small White (Pierisrapae)42

Green-veined
White (Pierisnapi)10

Brimstone (Gonepteryxrhamni)36

Wall (Lasiommatamegera)8

Speckled Wood
(Parargeaegeria)17

Small Heath (Coenonymphapamphilus)6

Red Admiral (Vanessaatalanta)39

Peacock (Aglaisio)7

Small
Tortoiseshell (Aglaisurticae)12

Duke of
Burgundy (Hamearislucina)46 – seen away from Newhaven at Heyshott
Down near Midhurst

About Me

I have watched and recorded wildlife since my childhood. I specialize in the insect orders of Lepidoptera (moths and butterflies) and Heteroptera (true bugs) and also record certain families of Coleoptera (beetles) and Diptera (flies), plus anything else which I consider myself proficient in.

I am a committee member of the Friends of Castle Hill Local Nature Reserve, which is based on and around the cliffs by Newhaven Fort in Newhaven and share a weekly transect walk during the recording season.

I am a member of the Amateur Entomologists' Society, the British Entomological and Natural History Society, the Sussex Moth Group, and Butterfly Conservation (Sussex)

I lead a number of public moth-recording events each year, usually in partnership with Lewes District Council.

All of my records are shared with the Sussex Biodiversity Record Centre at Woods Mill near Henfield and with individual County Recorders.